Date: Tue, 12 May 2020 14:32:29 +0000 From: Rick Macklem <rmacklem@uoguelph.ca> To: Benjamin Kaduk <bjkfbsd@gmail.com> Cc: John Baldwin <jhb@FreeBSD.org>, Rick Macklem <rmacklem@FreeBSD.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-projects@freebsd.org" <svn-src-projects@freebsd.org> Subject: Re: svn commit: r360859 - projects/nfs-over-tls/sys/rpc Message-ID: <QB1PR01MB3649B6EB237AE6392DF78A2EDDBE0@QB1PR01MB3649.CANPRD01.PROD.OUTLOOK.COM> In-Reply-To: <CAJ5_RoBw-vyPH1EdeKHS=a_kCm3HPoiAkpA%2BrTxhPYcqf3Lz-w@mail.gmail.com> References: <202005100017.04A0Hd7I058863@repo.freebsd.org> <6739df0b-e621-2ca5-8f92-821822733772@FreeBSD.org> <QB1PR01MB3649E7E08BDFE39C4B8B70A4DDBE0@QB1PR01MB3649.CANPRD01.PROD.OUTLOOK.COM> <QB1PR01MB3649282401A7562B36D3F84EDDBE0@QB1PR01MB3649.CANPRD01.PROD.OUTLOOK.COM> <QB1PR01MB36494D1076388A2AD64F5B02DDBE0@QB1PR01MB3649.CANPRD01.PROD.OUTLOOK.COM>, <CAJ5_RoBw-vyPH1EdeKHS=a_kCm3HPoiAkpA%2BrTxhPYcqf3Lz-w@mail.gmail.com>
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Benjamin Kaduk wrote: [stuff snipped] >You can avoid having to play games with putting stuff back on the socket >receive buffer by using a custom BIO implementation in userspace that knows >how to inject the received message. >Rick Macklem wrote: >>Actually, what might work for the krpc code is a new MSG_TLSAPPDATA >>flag for soreceive_generic(), which says "if the record is not application >>data, return an error". (Sort of the opposite of what you said above, but >>would perform the same thing.) >>This could be used for the krpc soreceive() calls, so that the non-application >>data record remains on the socket's receive buffer. Well, I'd find it a lot easier to implement MSG_TLSAPPDATA, since I've been looking at soreceive_generic() recently. I'm guessing that a custom BIO would need to be written and the upstreamed to openssl? Does anyone else (John maybe) have a preference? >>Then the krpc could do the upcall when the error is returned by soreceive() >>and the userland daemon could do an SSL_read() with >>SSL_MODE_AUTO_RETRY turned off. If I understand the man page, that will >>make SSL_read() process the non-application data record but return with an >>error of SSL_ERROR_WANT_READ without taking application data off the >>socket's receive buffer queue. > >The typical way to consume non-application-data records without hanging trying >to read any application data is to do a zero-length read. This still gets far enough >into the state machine machinery to do the job before checking that the length >is nonzero. Oh, that's useful info. I recall trying it months ago and it didn't seem to work. Maybe I was just seeing the failure and not realizing that it had worked but returned failure. I'll play with this using my userland test daemons. [most stuff snipped] >In the early-data case things are more complicated. Calling regular SSL_read() will >drive the handshake to completion, and there's a separate function to call to just >try to read early data. (You could also configure things to fully deny early data which >would probably be easier.) Thanks. Good suggestion. I've never known what to do with the early data when I played with the test daemons. (Again, I just threw it away.) Btw, I think I can test this using TLS1.2 because when one end does SSL_shutdown(), TLS1.2 sends an "alert close" and I can try handling that. Thanks for the comments, rick -Ben I might be stuck having the daemon do an SSL_read() for one application data record and then it can pass that data back down into the kernel to be prepended on the queue of received application data. >(I wouldn't want to MSG_PEEK for every record, since these will be rare.) >I also do already have code that blocks kernel reception when the upcall >to do the handshake is done, so the same could be used in this case. > >There is the slight trick that the client krpc code is in a socket upcall that can't sleep, >so I'll have to hand it off to some other thread that can sleep when I need to do it. > >Thanks for the hints, rick rick -- John Baldwin _______________________________________________ svn-src-projects@freebsd.org<mailto:svn-src-projects@freebsd.org> mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-projects To unsubscribe, send any mail to "svn-src-projects-unsubscribe@freebsd.org<mailto:svn-src-projects-unsubscribe@freebsd.org>"
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